Packing fluids are often used in subterranean operations. These fluids are placed into an annulus between a first tubing and a second tubing or the walls of a well bore. The packing fluid acts to insulate a first fluid (e.g., a hydrocarbon fluid) that may be located within the first tubing from the environment surrounding the first tubing or the second tubing to enable optimum recovery of the hydrocarbon fluid. For instance, if the surrounding environment is very cold, the packing fluid protects the first fluid in the first tubing from the environment so that it can efficiently flow through the production tubing, e.g., the first tubing, to other facilities. This is desirable because heat transfer can cause problems such as the precipitation of heavier hydrocarbons, severe reductions in flow rate, and in some cases, casing collapse. Additionally, when used in packer applications, a required amount of hydrostatic head pressure is needed. Thus, higher density packing fluids are often used provide the requisite hydrostatic force. Packing fluids are also used for similar applications involving pipelines for similar purposes, e.g., to protect a fluid located within the pipeline from the surrounding environmental conditions so that the fluid can efficiently flow through the pipeline. Packing fluids can be used in other applications as well, wherein it is desirable to control heat transfer. These applications may or may not involve hydrocarbons.
Cesium formate is often used in packing fluids because it is extremely soluble in water. Nonetheless, cesium formate is expensive, can cause corrosion problems such as hydrogen stress corrosion cracking and hydrogen embrittlement, and is not always sufficient to weight up the fluid. Localized corrosion, pitting and stress corrosion cracking are particularly problematic and related to a high risk of unpredictable and rapid failure of metal integrity. Pitting corrosion and stress corrosion cracking are common and frequently occur in well tubulars constructed from so-called corrosion resistant alloys. Corrosion inhibitors have little or no effect and can actually initiate corrosion. Hydrogen embrittlement is a brittle mechanical fracture of high-strength steels caused when atomic hydrogen dissolves in the crystal structure of a metal rather than forming hydrogen gas. It typically occurs in corrosive environments under constant tensile stress, similar to hydrogen stress corrosion cracking. The most common form is sulphide stress cracking, which occurs when stressed metal is exposed to water containing hydrogen sulphide or other sulphur compounds, generally under aerobic conditions.